This invention relates to the field of metalworking and more particularly to a method for welding finite metal bands into continuous bands during continuous processing of supply coils of the metal bands. The invention further relates to an apparatus for carrying out the method.
In order to be able to perform without interruption either a finishing or manufacturing operation using finite-length metal bands wound into so-called coils, it is necessary to weld the finite-length bands together without thereby interrupting the continuous further operation. In order to attain this goal, it is necessary to store a continously moving band material of a length adequate to permit the manufacturing unit to be continuously supplied from the storage of material during the welding cycle.
One method and apparatus for its implementation is known from German Pat. No. 2,934,115. In this procedure the moving band material is, for a specific duration, shaped and stored in the form of a band spool and then subsequently drawn from its spooled state for continuous further manufacturing or finishing. During this known process the band lengths to be welded are grasped at both ends and then wound jointly on a band spool in two layers and from opposite sides turning in the same direction of rotation. The cylindrically-shaped band spools consist of two sections, which include the welding unit so that the welding cycle is performed as the cylinder rotates. Prior to the method and apparatus described in German Pat. No. 2,934,115, moving band material had to be stored in the form of a band spool in one layer on a large cylinder for a specific duration, and an additional so-called feed-end twist length and a so-called discharge twist length of relatively extensive length were required. The German patented method has the advantage that its spatial requirements are substantially smaller. Admittedly, however, in this method a single cylinder is insufficient. Continuous manufacturing over a extended period of time rather requires a number of cylinders continuously interchanging positions and also requires a buffer length to handle the band material collected as the cylinders are repositioned.
It is desirable to have a method and apparatus which no longer requires either the relatively complicated two-section cylinder design or the relatively extensive repositioning process of the cylinders, or even an additional band buffer required by the previous method and apparatus.
With such a desired method and apparatus, one advantage is, that due to the relatively large diameter of the single storage coil, the welding device is not spatially restricted and is accessible with relative ease. In addition, the apparatus can be so constructed that it only requires simple rotary drives held in a constant mutual position and regulated accordingly. Particularly the elimination of the repositioning drives would provide a substantial simplification of the engineering complexity and thus also a reduction of the tendency for the system to malfunction.